Operation button



FIG. 1 is a perspective view of our design for an operation button;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a left side elevational view thereof; and,

FIG. 8 is a cross-sectional view taken along line 8—8 of FIG. 2.

The broken lines are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for an operation button, as shown and described. 